Hammond 1630SEA, worth trying?

[Fuling]

Hi,

Since the old 1628SE from Hammond have some serious problems in the HF (dips 6dB at 13Khz and then rolls of) I´m a bit reluctant to buy stuff from the same series.
The 1630SEA is a new model (3,5k 135mA 44H), has anyone tried it?

I´m collecting parts for a slightly weird project, an SE amp with 808´s as output tubes. Some people might advice me to choose something better than 808, but I´ve built an amp with 811A that worked pretty darn well and 808 should be quite similar to work with (and they look much better!).

There are two or three 808 SE projects online and all of them seem to run on low B+ with 2,5k plate loads, I want to use a little more voltage and higher impedance so 3,5K seems reasonable.
Another option would be to run them at close to 500V with 5k plate load, similar to my 811A amp.

Before I start spending money I want to here some opinions about the Hammond 1630SEA, if they perform anything like the 1628SE they´re not worth a dime for me.

[satelitis]

Originally posted by Fuling
Hi,

Since the old 1628SE from Hammond have some serious problems in the HF (dips 6dB at 13Khz and then rolls of) I´m a bit reluctant to buy stuff from the same series.
The 1630SEA is a new model (3,5k 135mA 44H), has anyone tried it?

I´m collecting parts for a slightly weird project, an SE amp with 808´s as output tubes. Some people might advice me to choose something better than 808, but I´ve built an amp with 811A that worked pretty darn well and 808 should be quite similar to work with (and they look much better!).

There are two or three 808 SE projects online and all of them seem to run on low B+ with 2,5k plate loads, I want to use a little more voltage and higher impedance so 3,5K seems reasonable.
Another option would be to run them at close to 500V with 5k plate load, similar to my 811A amp.

Before I start spending money I want to here some opinions about the Hammond 1630SEA, if they perform anything like the 1628SE they´re not worth a dime for me.

Good day
I don't think it is a weird project at all. This tube may play VERY WELL if you drive it right. I build a SE amplifier using 808 a few months ago using an Hammond 1627 transformer and the results was very good. I first use a pentode 6SJ7 as 1st stage but right after I change to 1/2 6SL7 triode. If you have all the parts I think it is worth to try this project some time. Have a look here for some pictures and schematic.

http://briefcase.pathfinder.gr/browse/satelitis/48034

Chris

[Fuling]

Yes, transmitter triodes in SE class A2 curcits can sound very good if they have decent drive stages.
1627SE is another option, but I´d prefer a little little higher impedance if possible.

[satelitis]

Originally posted by Fuling
Yes, transmitter triodes in SE class A2 curcits can sound very good if they have decent drive stages.
1627SE is another option, but I´d prefer a little little higher impedance if possible.

I do believe also that 5K will be much better for the 808. I dont know about the new 1630SEA but the old 1628 was really a pain in the *ss.
Regarding the A2 I do believe that it sounds very nice as fas as you choose the right driver stage. I think that if I was going to build this project again I would use an interstage transformer in order to avoid this pentode cathode follower stage. (you see i hate pentodes...).

[Fuling]

I´ve seen a few Japanese 808 projects and all of them seem to use 2,5k plate loads, but I also believe 4-5k would be better.
1628 had some major design fault, and I don´t know if they´re corrected in the new SEA version.

I don´t know about those inverting interstage transformers, seems like a mess to get them working properly. I´ll probably use a mosfet follower.

[satelitis]

I don´t know about those inverting interstage transformers, seems like a mess to get them working properly. I´ll probably use a mosfet follower. [/B][/QUOTE]

You have Lundahl next to you! It is worth to try a LL1660 Intertage for example in reasonable price.

[Fuling]

I already have a pair of LL1671/50mA interstage transformers, perhaps they would work in inverting mode if I wire them 2:1.
I think some German guy used the very same transformers that way in a 838 A2 project. Might be worth a try, but I believe a Mosfet technically would be better.

[EC8010]

My understanding is that the 1628SE was a one-off ****-up and was not scaled to produce other models in the series.

[Fuling]

That´s my understanding too, a friend of mine has used a few of those 16XXSE-transformers and 1628 seems to be the only one with a problematic frequency responce.
Still, it would be great to hear something from someone who actually owns a pair.
Hammond transformers are cheap compared to other brands, but it´s still some serious money.

[tubelab.com]

I can't speak for the 1630SEA, but I tested both the 1628SE and the 1628SEA. The 1628SE's that I have are not as bad as the ones that others have tested but they do have a serious notch in the response in the audio band. The 1628SEA's do not have this notch, but do not make the claimed 20Hz to 20KHz +/- 1DB either.

Look here for further info:

Why are Hammond SE OPTs dissed? Heavier than the competition...